In many processes or test procedures, the need to measure specific or general pressure can be paramount in controlling the respective process or for understanding the conditions being encountered. A variety of pressure sensor designs are typically used to measure such a pressure, including strain gauge sensors, Bourdon tubes, quartz sensors, and hybrids of any of the above. For example, Bourdon tube designs exist whereby a tube is open and fixed at one end, with the interior of the tube being exposed to system pressure for pressure monitoring. The other end of the tube is closed and is free to move. When the tube is exposed to system pressure, the movement of the free end of the tube is directly related to the magnitude of the system pressure. The free end of the tube may be connected via a direct acting mechanical linkage that is coupled to a pointer that travels over a calibrated scale readout for providing an indication of the system pressure.
Another Bourdon tube design uses the movement of the Bourdon tube to stress a quartz crystal. The change in reactance of the crystal under stress can be measured locally within the pressure gauge and referenced electronically to a calibrated look-up table for the actual pressure. Design variations of the above measure changes in resonance or strain via strain gauges.
Although the reliability of the basic Bourdon tube is very high, the adhesives and electronic components used in current Bourdon tube quartz crystal designs are very susceptible to failure, especially at high local or ambient temperatures. For example, at temperatures greater than 125.degree. C. the electronic circuitry associated with a strain gauge or a quartz crystal degrades such that the reliability of the system is jeopardized in terms of both accuracy and functionality. Additionally, the various adhesives used with such a strain gauge or quartz crystal are prone to failure at temperatures greater than 125.degree. C. Therefore, there exists a need for a reliable pressure sensor design, which is particularly suited for use at high local or ambient temperature conditions.